The invention relates to a method for producing a light-alloy bearing bushing having a rough external surface, for an internal combustion engine. Such a method is known from DE 19958185. There, the rough surface of the light-alloy bearing bushing is produced, during casting of the bearing bushing using the lost-foam process, in that the lost-foam casting model of the bearing bushing has an external particle layer with undercuts, which results in a corresponding undercut shape of the external surface of the cast bearing bushing. The rough surface of the bearing bushing is a prerequisite for the fact that a good connection between the bearing bushing and the integral casting material occurs during casting of the bearing bushing.
Furthermore, the production of a brake drum having a rough external surface structure, using the spin casting method, is known from CH 366 636 A, in which method the roughness is produced by means of a refractory mass that is applied to the surface of the casting mold in liquid form and is extremely porous in the dry state, in that the casting metal penetrates into the pores of this lining. However, the use of a spin casting method or pressure casting method is required for this, since here the mere hydrostatic pressure of the molten metal in the form is not sufficient for penetration into the pores of the refractory mass, such as in the chill mold method, for example. Another disadvantage consists of the compulsory mechanical finishing, for example sand blasting, in order to free the surface of the bushing from the adhesions of the refractory mass, so that a quality-appropriate subsequent casting process of the brake drum is assured in the subsequent steps. This type of mechanical finishing reduces the desired roughness to a rather significant extent.
EP 1 226 889 A discloses a method for the production of a rough surface of a work piece, using the sand casting method, in which a lost mold, particularly a sand mold, is also used for casting. Here, the rough structure on the work piece is produced by the sand structure of the casting sand, into which metal oxides or particles that can melt are mixed in order to increase the roughness. It is a disadvantage that a lost mold is used, that additives must be mixed in, and that subsequent mechanical finishing of the rough work piece surface, for example by means of sand blasting, is required.